Method of and apparatus for heating fluids



Patented June 2, 1942 l 'I Y UNITED STATES PATENT OFFICE 2,285,037 METHOD OF AND APPARATUS FOR HEATING FLUIDS y Walter E. Lobo, Westfield, N. J., assignor to Gase# line Products Company Inc., Newark, N. J., a corporation of Delaware Application February 18, 1938,` Serial No. 191,269

9 Claims. (Cl. 19E-116) This invention relates to methods of and appreferably used as a reboiler coil for heating conparatus for heating fluids, more particularly to densate oil or the like passing therethrough from methods of and apparatus for heating hydroa fractionating tower or the like, but these heater carbon fluids. tubes lmay also be used for heating or cracking One form of apparatus constructed to embody separate streams of oil, if desired.

my invention includes a furnaceV having a radi- One method contemplated by my invention inant section and a convection section, each seccludes passing hydrocarbon fluids under supertion being provided with heater tubes. A sepaatmospheric pressure through Wall tubes and rate soaker section is provided for supplying roof tubes in the radiant section of the furnace heat to th'e hydrocarbon uids undergoing con- 10 whereby. the hydrocarbon fluids are heated to the version, the soaker section being heated by hot desired conversiontemperature and then through products of combustion leaving the furnace. heater tubes in the soaker section wherein the A plurality of ducts is provided for conducting hydrocarbon iiuids are maintained at the proper selected portions of theproducts of combustion 'conversion temperature for the desired time. to the soaker section and means are provided in The temperature of the hot products of combusthe ducts for controlling the temperature of the tion being passed to the soaker section through to the soaker section. A plurality of ducts is leaving the radiant section of the furnace with' provided near the bottom portion of the conveccooler products of combustion leaving the bottom tion section for conducting relatively hot prodportion of the convection section of the furnace. ucts of combustion to the soaker section. A The temperature of the hot products, of complurality of ducts communicating with the furbustion being passed to the soaker section may nace above the convection section is provided for be further controlled by admitting air or other conducting hot products of combustion leaving cool gas to the stream of hot gases before pas-v the radiant section to the soaker section before sage to the soaker section or by by-passing all the hot gases pass through the convection secor a portion of the hot products of combustion tom of the convection section. The last menthe stack, while reducing or cutting oi the suptioned ducts preferably communicate with the plyr of hot gases from the upper ducts which are rst mentioned ducts leading from the bottom adapted to convey the hot gases directly from portion of the convection section so that the hot the radiant section of the furnace.

products of combustion from the two portions By the arrangement of ducts I am enabled to of the furnace are mixed before passage to 'the 35 control the input of heat to the soaker section soaker section. Instead of using pluralities of by passing hot flue gas or products of combus- SetS 0f duCSS, Single ducts may be used. tion to the soaker section or a blend of hot and Another duct .is provided Which communicates cooler gases to the soaker section. If desired, with the ducto loading from the bottom Portion no heat need be added to the soaker section and thfggnsxolgvfg'seanr 40 all the flue gas or hot products of combustion soaker section and passed directly to the stack. ma b? ysseg alomld lthe s1? akir Sectmn g1' Another duct is provided for admitting air at rec .y m o e s ac aso I.) 0V e tneanq or atmospheric temperature into the hot products Cooling the Sfoaker Sectlon by lm roducmg au' or of Combustion passing to the Soaker section so cooling gas mto the soaker sectlon or mto the as to control the temperature of such combusflue gas or hot products of oombustlon bcmg tion products being passed to the soaker section. passed to the soakor sectlon' Blowers may bc Dampers are provided in the Various ducts in used to force the combustion products through order to control the amount of hot gases passing the ducts 1f d csucd to the soaker section, the amount of hot gases In the d'aWmg by-passed around the Soaker section and the .Figure 1 represents 2, lOIlglldIlal Vertical CIOSS amount; of air 0r cooling gas admitted t0 the hot section of one form of apparatus taken substangases passing to the soaker section. tially on line I-l of Figure 2, parts being broken The heater tubes in the convection section toaway to facilitate the disclosure; and

gether with iioor tubes in the radiant section are Figure z'represents a reduced transverse versection I4 and over the i ducts 46 tical cross section taken substantially on line 2-2 of Figure 1.

Referring now to the drawing, the reference character I6 designates a furnace or heating apparatus including a radiant section I2 and a convection section I4 separated by a bridge wall I6. Any suitable means such as burners I3 are provided for heating the radiant section I2. The radiant section is provided with wall tubes 2E), roof tubes 22 and floor tubes 24 all of which are disposed to be heated preponderantly by radiani-l heat. Other arrangements of heater tubes and additional heater tubes may be used, if desired. The convection section I4 is provided with heater tubes 26 which communicate with the floor tubes 24 through line 30.

A hydrocarbon fluid to be heated to a conversion temperature is passed through line 32 by pump 34, through wall tubes 26 and roof tubes 22. After being heated in the radiant section, the hydrocarbon liuids are passed through line 36 and through the heater tubes 38 in the soaker section 40. From the drawing it will be seen that I have provided a separate soaker section. The hydrocarbon t 43 are each provided the proper temperature in the soaker section 40,

are passed through line 42 and may treated, as is well known in the art, to separate hydrocarbons having the desired boiling range.

I have provided a plurality of ducts for conducting hot combustion gases from the radiant section and from the convection section to the for supplying heat to the soakducts. form` means whereby different amounts of combustion gases passed to the soaker section to control the heating thereof. A plurality of horizontally arranged ducts 46 and 48 communicate with the bottom portion of the convection section I4 for conducting hot combustion gases to the bottom portion of the soaker section 40. A plurality of horizontally arranged ducts and 52 communicate with the top portion of furnace I6 above the convection section I4 for conducting hot products of combustion from the radiant section I2 to the soalrer` section 40 before the hot products of combustion are passed through the convection heater tubes 26 therein.

In this way theY products of combustion leaving through the upper a higher temperature than the combustion products leaving through the lower ducts 46 and 48. Each of the horizontally arranged upper ducts 50 and 52 is provided with a vertically arranged portion 54 and the portions 54 communicate respectively with the lower horizontally arranged and 48 at a point intermediate the convection section and the soaker section so that the hot products of combustion from the upper and lower ducts will be mixed together before being introduced into the soals'er section. In the drawing I have only shown one of these vertical portions 54 but it will be understood that each horizontally arranged duct 50 and 52 has such a vertical portion.

In some instances it may be desirable to bypass the hot products of combustion passing through ducts 46 and 43 around the soaker section 40 directly to the stack. Such a construction includes ducts 56 and 58-which communicate respectively with the horizontally arranged lower ducts 46 and 48 at a point between the convection section I4 and the vertically arranged portions 54 of the upper ducts 50 and 52. .These ducts 56 and 58 converge-into a vertically armay be ducts 50 and 52 will be at ranged common duct 60 having a horizontally arranged portion 62 which leads directly into the stack 64. I have also included a duct 66 having a damper 68 and positioned between the soaker section 40 and the vertical portions 54 of the upper ducts 50 and 52, whereby air at atmospheric temperature or other cooling gases may be added to the hot products of combustion passing to the soaker section 40 in order to cool them to the proper temperature desired for the soaker section 4I).

The lower horizontally arranged ducts 46 and with a damper 10 positioned between the bypass duct 60 and the vertical portions 54 of the upper ducts 50 and 52. The ductsV 46 and 48 are each further provided with a damper 12 positioned between the vertically arranged portions 54 of the upper ducts 50 andv 52 and the duct 66. Each vertically arranged portion 54 oi the upper ducts 50 and 52 is provided with a damper 14.. The bypass duct 60 isprovidedwith a damper 16. By providing the various ducts and the dampers it will be apparent that the temperature of the hot gases being passed to the soaker section may be readily controlled. v

A separate stream oi hydrocarbon fluid is passed through line 80 by pump 82, through the heater tubes 26 in the convection section I4 and then through line 30 and floor tubes 24 in the radiant section I2 of the furnace I0. The hydrocarbon fluids after. .the desired amount oi heating are passed through line 84 and may be further treated as desired. The heater tubes 26 and iloor tubes 24 may be usedas a reboilcr for heating condensate oil from a iractionating tower, or may be used for heating or converting separate streams of fluids.'

In the drawing I have shown one form of apparatus suitable for practicing my inventionbut I am not to be restricted thereto as changes and modications may be made which are clearly within the contemplation of my invention.

Some examples of methods contemplated by my invention will now be given but it is to be understood that they are by way of illustration only and that I am not to be restricted thereto. My invention is especially adapted for the polymerization of hydrocarbon gases to convert such gases into higher boiling hydrocarbons containing gasoline. Hydrocarbon gases such as gases containing C2 to C4 hydrocarbons preheated to about 650 to 750 pressure of about 400 to 3000 pounds per square inch, preferably about 1800 pounds per square inch, are passed through the wall tubes 20 and roof tubes 22 in the radiant section I2 where they are heated to a conversion or polymerization temperature of about 750 to 1300 F., preferably about 1030 F. The heated gases are then passed through the soaker section 40 where further heat is supplied, if necessary, to maintain them at or slightly increase the conversion temperature. The converted or polymerized products leave the soaker section through line 42 at a temperature of about 1000 to l'F., preferably about 1030 F. to 1050 F. and under a pressure of about 1600 pounds per square inch.` Such products may be immediately quenched upon leaving the soaker 40 in any well known manner.

When using the heater tubes 26 in the convection section I4 and floor heater tubes 24 as a reboilcr coil for the passage of condensate liquid from .a fractionating tower, the hydrocarbon ilulds entering through line 86 are at a temper- F. while maintained under a l ature of about 500 to 550 F. and under a pressure of about 250 to 350 pounds per square inch. As the hydrocarbon fluids pass through the heater tubes 26 they absorb heat from the hot products of combustion passing through the convection section. 'I'he hydrocarbon fluids are further heated by passing through the floor tubes 24 of the radiant section I2 and leave the furnace through line 84 at a temperature of about 650 to '750 F. and under a pressure of about 150 to 250 pounds per square inch. The heater tubes 26 may be used to heat or crack other streams of fluids, under such conditions of temperature and pressure as desired. y

The method of controlling the temperature of the hot products of combustion passing to the soaker section 40 will now be described. With damper 16 in the bypass duct 60 and damper 68 in the duct 66 closed and with the other dampers 10, 12 and 14 open, it will .be seen that cooler products of combustion passing through the lower ducts 46 and 48 from the lower portion of the convection section I4 will be mixed with hotter products of combustion passing through the upper ducts 50 and 52 andthe admixed gases will be passed to the soaker section'40.

If the temperature of the combustion gases passing to the soaker section 40 is too low, damper 14 is opened more and damper 1B is closed a little to permit the passage of more of the hotter products of combustion through ducts 50 and 52 than of the cooler products of combustion through the lower ducts 46 and 48. Or damper 10 may be completely closed. If' the temperature of the gases is tooA high, air or other cooling gas may be added through duct 66 by opening damper 68 the proper amount. Instead of admitting air or other cooling gas, the damper 14A in the upper ducts &1 and 52 may be moved to admit less of the hot products of combustion passing therethrough and damper 1 0 may be opened to a greater degree to permit more of the cooler combustion gases from the bottom portion of the convection section to pass to the soaker section 40.

If desired, dampers 10, 12 and 14 may be moved` to closed position and damper 16 in bypassduot 60 opened so as to bypass all the hot products of combustion around the soaker section 40 to the stack 64. With the dampers 10, 12 and 14 closed and if it is desired to cool the soaker section 40, air or other cooling gas maybe admitted through duct 66. This is particularly advantageous when an eXotherrnic polymerization reaction is taking place in soaker 4 From the above it will be seen that by manipulation of dampers in the various ducts, the temperature of the products of combustion passing to the soaker section 40 may be readily controlled to obtain any desired ternperature in the soaker section.

In another form of method controlled by my invention a hydrocarbon iiuid or uids such as a gas oil stock to be cracked or the like is passed through the wall tubes 20 and roof tubes 22 wherein the gas oil is heated to a temperature of about 925 to 1100 F. while maintained under superatmospheric pressure of about 200 to 1000 pounds per square inch. Theiheated gas oil under super-atmospheric pressure and at a temperature of about 925 to 1100u F. is then passed through the soaker section 46 whereinthe proper heat is maintained to complete the conversion of the gas oil without obtaining objectionable coking in the heater tubes 38. The dampers in the ducts are regulated to control the Aheating of the soaker section as above described. The products of conversion leaving the soaker section 40 may be further treated as desired to separate lower boiling hydrocarbons having the desired boiling range. In this form of the invention a separate streamV of hydrocarbon fiuid or Iiuids is also passed through heater tubes 26 in the convection section I4 and through the oor tubes 24 in the radiant section I2 of the furnace I0.

My invention may be readily applied to a conventional furnace having a pair of separately fired radiant sections and a common convection section receiving combustion gases from each of the separately fired radiant sections. As is well understood in such a furnace, tubes may be placed along the `four walls, roof, and i'loor of each separately fired radiant section and similar tubes may be placed in the convection section. In applying my invention to a furnace of this character, a duct or ducts similar to the ducts 5i) and 52 may .be connected to the upper part of the convection section whereby a part of the hot combustion gases may be withdrawn prior to passage through the convection section, while another duct or ducts, similar to the ducts 46 and 48, may be connected to the lower part of the convection section for withdrawing cooler combustion gases which have passed therethrough and over the tubes therein.

The convection section may be formed by suitable bridge'walls separating the separately fired radiant sections from each other and the bridge walls are preferably located in the `center of the furnace, thereby forming a convection section intermedia-te the separately fired-radiant sections. If desired, the convection section may be placed overhead on top of the radiant sections, preferably at the middle of the furnace, and with such a structure, ducts are placed at the upper and lower portions of the convection section for withdrawing cooler respectively, in the manner described. Combustion gases withdrawn from furnaces of this character may be passed to or by-passed around a soaking section, similar to the soaking section 40, in the manner described in detail in connection with Fig. 1.

While I have shown several examples of my invention it is to .be understood that they are by way of illustration only, and many variations and modifications of my invention may be made without digressingv from the spirit of my invention.

I claim:

1. An apparatus posed in the by heat is supplied to the uid and the combustion gases are reduced in temperature, a separate heating section provided with heater tubes communicating directly with said heater tubes in said radiant section, and means whereby heat is supplied to said separate heating section, said means including a plurality of ducts, one o'f said ducts extending from said convection section and adapted to convey the cooled combustion gases from said convection section to said separate heating section and another duct extending from and hot combustion gases,v

said radiant section to said separate heating section, whereby products of vcombustion having different temperaturesv are delivered to' said separate heating section and the temperature of said separate heating section may be controlled by varying the amounts of products of combustion passing through said ducts.

2. An apparatus of the character described adapted for heating hydrocarbon fluids to conversion temperatures, which includes a furnace having a radiantsection and a convection section disposed to receive furnace gases from said radiant section, means for supplying hot products of combustion to said radiant section', heater tubes in said radiant section for conveying fluidv to be heated and disposed to receive radiant. heat, heater tubes'in said convection section for conveying fluid to be heated and disposed in the path of the combustion gases whereby heat is supplied to the fluid and the combustion gases are reduced in temperature, a soaker section provided with heater tubes communicating directly with said heater tubes in said radiant section, a stack adapted to gases and means whereby heat is supplied to'said soaker section, said means including a plurality of ducts provided with control means, one of said ducts connecting said convection section with said soaker section and adapted to convey the cooled combustion gases to'said soaker section, another duct being adapted to bypass at least a portion of the products of combustion -fromy said first mentioned duct to said stack, and another duct connecting said radiant section with said iirst mentioned duct beyond said bypass duct whereby products of combustion having dif-Y ferent temperatures are mixed and delivered to said soaker section through saidy rst and last mentioned ducts and the temperature of said soaker section may be controlled by varying the amounts of products of combustion passing through said ducts.

3. An apparatus of the character described adapted for heating uids which includes a furnace having a radiant section and a convection section disposed to receive furnace gases from said radiant section, means for supplying hot products of combustion to said radiant section, heater tubes in said radiant section for conveying uid to be heated and disposed to receive radiant heat, heater tubes in said convection section for conveying fluid to be heated and disposed in the path of the combustion gases Whereby heat is supplied to the fluid and the combustion gases are reduced in temperature, a separate heating section provided with heater tubes communicating directly with saidl heater tubes in said radiant section, and means whereby heat is supplied to said separate heating section, said means` including a plurality of ducts, one of said ducts connecting said convection section with said separate heating section and adapted to convey the cooled combustion gases from said convecti'onV section tosaid separate heating section and another of said ducts connecting the radiant sectionl with said first mentioned duct, whereby products of combustion having different temperatures are mixed and delivered to said separate', heating section and the temperature of said separateV heating section may be controlled by varying the amounts of products of combustion passing: through said ducts, and means whereby at least a .portion of the products of combustion kfrom the bottom portion of said convection sec- CIR carry awa-y waste combustion v version temperature heat, means t radiant section whereby tionV may be withdrawn from said iirst mentioned duct and removed as waste gas.

4. An apparatus of the character described adapted for heating hydrocarbon fluids including, in combination, a furnace having a radiant section and a convection section separated by a bridge wall, means for supplying hot products of combustion to said radiant section, heater tubes in said radiant section adapted to convey hydrocarbon` fluids to be heated, heater tubes in s'aid convection section adapted to convey a separate stream of iiuid to be heated, a soaker section provided with heater tubes in communication with said heater tubes in said radiant section and adapted to convey the heated hydrocarbon fiuids, and meansfor supplying heat to said soaker section, said means including a plurality of ducts adapted to conduct products of combustion from said furnace to said soaker section, one of said ducts extending from the bottom portion of said convection section for conveying rela.. tively cool combustion gases and another of said ducts extending from said radiant section for conveying hot combustion gases therefrom before passing through said convection section,

' said second mentioned duct-communicating with said first mentioned duct whereby the combustion gases are mixed before passing Jto-said soaker section, and means for controlling ythe amounts of combustion gases passing through said ducts to regulate the temperature of the gases supplied to said soaker section.

5. An apparatus of the character described adapted for heating hydrocarbon iiuids to conwhich includes a furnace having` a radiant section and a convection section, heater tubes in said radiant section for conducting a hydrocarbon fluid under superatmospheric pressure and disposed to receive radiant for supplying hot products of combustion to said radiant section for supplying heat to saidheater tubes and heating the hydrocarbon fluid therein to a relatively high temperature, a separate heating section provided with heater tubes communicating directly with said heater tubes in said radiant section whereby the heated hydrocarbon fluid passes from said radiant section to said separate heating section and is further heated therein, heater tubes in said convection section disposed in the path of the combustion gases and adapted for conducting a separate stream of hydrocarbon fluid through said convection section, said convection section being adapted to receive combustion products from said the separate stream of hydrocarbon isheated and the combustion products are cooled as they pass through said convection section, ducts for supplying hot combustion products from said radiant section and convection section to said separate heating section, one of said ducts being adapted to convey cooled combustion gases from said convection section and another duct extending from said radiant section, and means in said ducts for controlling the amounts of combustion products passing through said ducts for controlling the temperature of said separate heating section.

6. A process for heating hydrocarbon fluids to conversion temperatures which comprises passing hydrocarbon fluid under superatmospheric pressure through a confined passageway disposed in a radiant section of a furnace adapted to supply radiant heat thereto, supplying hot combustion gases to said radiant section to raise the hydrocarbon fluid to a relatively high temperature, passing the highly heated hydrocarbon heater tubes in said radiant section for conveying liuid directly to a soaker section disposed in a uid to be heated and disposed to receive radiant separate heating zone to supply additional heat heat, heater tubes in said convection section for thereto, passing furnace gases from said radiant conveying fluid to be heated and disposed in the section to al convection section, passing a sepa- 5 path of the convection gases, a separate heating rate stream of fluid through said convection secsection provided with heater tubes comm-unicattion of the furnace to heat the liuid and reing directly With said heater tubesinsaid radiant duce the temperature of the hot gases passing section, and means whereby heat is supplied to gases from said radiant section to said separate cluding a plurality of ducts, one of said ducts passing the admixed gases to said separate heatl5 section and another of said ducts being cony ing zone. nected to remove combustion gases flowing from 7. In a process for heating hydrocarbon uids said radiant section to said convection section to conversion temperatures wherein hydrocarbon and to conduct the gases so removed to said uids are passed through a furnace having a heating section, whereby combustion gases havradiant section and a convection section dising different temperatures are mixed and delivcarbon fluid under superatmospheric pressure be controlled by varying the amounts of comthrough a conned passageway disposed in the bustion gases passing through said ducts. radiant section of the furnace to receive radiant 9. A I )rOCSSS fOr heating hydrocarbon fluids to heat, supplying hot combustion gases to said conversion temperatures which comprises passsection disposed in a separate heating zone to radiant SeCtiOn t0 apply radiant heat 120 Said pasamount of hot combustion gases from said radi- 4o temperature of the combustion gases passing said radiant section, means for supplying hot WALTER E. LOBO. 

